This study explores the irregularity and complexity of strong earthquake ground motions from the perspective of fractal geometry, and constructs a relation with the frequency content of the ground motions. The box-cou...This study explores the irregularity and complexity of strong earthquake ground motions from the perspective of fractal geometry, and constructs a relation with the frequency content of the ground motions. The box-counting fractal dimensions and five representative period parameters of near-fault ground motions from the Chi-Chi and Northridge earthquakes are calculated and compared. Numerical results indicate that the acceleration and velocity time histories of ground motions present the statistical fractal property, and the dominant pulses of near-fault ground motions have a significant influence on their box dimensions and periods. Further, the average box dimension of near-fault impulsive ground motions is smaller, and their irregular degree of wave forms is lower. Moreover, the box dimensions of ground motions reflect their frequency properties to a large extent, and can be regarded as an alternative indicator to represent their frequency content. Finally, the box dimension D of the acceleration histories shows a considerably negative correlation with the mean period T. Meanwhile, the box dimension of the velocity histories Dye is negatively correlated with the characteristic period T and improved characteristic period Tgi.展开更多
<strong>Purpose: </strong><span style="font-family:;" "=""><span style="font-family:Verdana;">The purpose of this study was to assess the impact of free caesa...<strong>Purpose: </strong><span style="font-family:;" "=""><span style="font-family:Verdana;">The purpose of this study was to assess the impact of free caesarean section on maternal-fetal prognosis. </span><b><span style="font-family:Verdana;">Materials and Methods:</span></b><span style="font-family:Verdana;"> This was a descriptive, cross-sectional, comparative analytical study of one year of non-free caesarean section and three years of free with retrospective data collection. Our study took place from January 1, 2004 to December 31, 2004 and from January 1, 2007 to December 31, 2009. </span><b><span style="font-family:Verdana;">Results:</span></b><span style="font-family:Verdana;"> Caesarean section completion rates are 1.28%, 1.30%, 1.53%, 1.32% respectively in 2004, 2007, 2008, 2009. The average age was 27 years with extremes of 15 to 40 years. The peak of evacuations was recorded in 2007 with a rate of 89.4% and the peak of direct admissions in 2009 with a rate of 14.9%. An adequate means of transport was used in 77.20%. In 22.80% of cases an inadequate means was used. The indications of caesarean sections were dominated by preeclampsi</span></span><span style="font-family:Verdana;">a</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> 211/1045 caesarean section followed by acute fetal suffering 179/1045;86/1045;placenta previa 64/1045;presentations of the shoulder </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> 53/1045;pre-rupture syndrome 44/1045;retro-placental hematoma 27/1045. In terms of maternal prognosis: we noted maternal deaths with a rate of 2.4%</span></span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">4%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">4</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">3%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">0.4% respectively in 2004</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2007</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2008</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2009. And stillbirth rates were 17.6%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">22</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">4%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">27</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">4%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">21.7% respectively in 2004</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2007</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2008</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2009</span><span style="font-family:Verdana;">. </span><span style="font-family:;" "=""><span style="font-family:Verdana;">The average length of hospitalization was 10 days. </span><b><span style="font-family:Verdana;">Conclusion:</span></b><span style="font-family:Verdana;"> Free caesarean section would be a factor in improving the maternal-fetal prognosis.</span></span>展开更多
基金National Natural Science Foundation of China under Grant Nos.50978047 and 11332004National Basic Research Program of China under Grant No.2010CB832703
文摘This study explores the irregularity and complexity of strong earthquake ground motions from the perspective of fractal geometry, and constructs a relation with the frequency content of the ground motions. The box-counting fractal dimensions and five representative period parameters of near-fault ground motions from the Chi-Chi and Northridge earthquakes are calculated and compared. Numerical results indicate that the acceleration and velocity time histories of ground motions present the statistical fractal property, and the dominant pulses of near-fault ground motions have a significant influence on their box dimensions and periods. Further, the average box dimension of near-fault impulsive ground motions is smaller, and their irregular degree of wave forms is lower. Moreover, the box dimensions of ground motions reflect their frequency properties to a large extent, and can be regarded as an alternative indicator to represent their frequency content. Finally, the box dimension D of the acceleration histories shows a considerably negative correlation with the mean period T. Meanwhile, the box dimension of the velocity histories Dye is negatively correlated with the characteristic period T and improved characteristic period Tgi.
文摘<strong>Purpose: </strong><span style="font-family:;" "=""><span style="font-family:Verdana;">The purpose of this study was to assess the impact of free caesarean section on maternal-fetal prognosis. </span><b><span style="font-family:Verdana;">Materials and Methods:</span></b><span style="font-family:Verdana;"> This was a descriptive, cross-sectional, comparative analytical study of one year of non-free caesarean section and three years of free with retrospective data collection. Our study took place from January 1, 2004 to December 31, 2004 and from January 1, 2007 to December 31, 2009. </span><b><span style="font-family:Verdana;">Results:</span></b><span style="font-family:Verdana;"> Caesarean section completion rates are 1.28%, 1.30%, 1.53%, 1.32% respectively in 2004, 2007, 2008, 2009. The average age was 27 years with extremes of 15 to 40 years. The peak of evacuations was recorded in 2007 with a rate of 89.4% and the peak of direct admissions in 2009 with a rate of 14.9%. An adequate means of transport was used in 77.20%. In 22.80% of cases an inadequate means was used. The indications of caesarean sections were dominated by preeclampsi</span></span><span style="font-family:Verdana;">a</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> 211/1045 caesarean section followed by acute fetal suffering 179/1045;86/1045;placenta previa 64/1045;presentations of the shoulder </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> 53/1045;pre-rupture syndrome 44/1045;retro-placental hematoma 27/1045. In terms of maternal prognosis: we noted maternal deaths with a rate of 2.4%</span></span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">4%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">4</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">3%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">0.4% respectively in 2004</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2007</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2008</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2009. And stillbirth rates were 17.6%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">22</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">4%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">27</span><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;">4%</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">21.7% respectively in 2004</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2007</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2008</span><span style="font-family:Verdana;">, </span><span style="font-family:Verdana;">2009</span><span style="font-family:Verdana;">. </span><span style="font-family:;" "=""><span style="font-family:Verdana;">The average length of hospitalization was 10 days. </span><b><span style="font-family:Verdana;">Conclusion:</span></b><span style="font-family:Verdana;"> Free caesarean section would be a factor in improving the maternal-fetal prognosis.</span></span>
